| 摘要 |
<p>Exposure light can pass through a partition wall flat plate (64) via an opening (66a) of a second wall (66) and an opening (62a) of a first wall (6). The partition wall flat plate is supported least at three points so that a first opposing face (Sb) of the first wall and a second opposing face (Sc) of the second wall are opposed respectively to one face of the partition wall flat plate and the other face through a first and a second clearance, and a third opposing face of a third wall (CW) is opposed to the entire side face of the partition wall flat plate through a third clearance. The third clearance is connected to an air exhaust passage (58). This means that unnecessary stress is not applied to the partition wall flat plate and that, because gas in the third clearance is forcedly exhausted outside, even entry of gas in a space region on one face side of the partition wall flat plate to a space region on the other face side is prevented, so that gas in the two space regions is effectively prevented from being mixed.</p> |
